Developed by Robert Bosch, GmBH, in 1991, the Controller Area Network (CAN) is employed widely in modern automobiles, medical instrumentation, tactical vehicles, building automation, metropolitan transportation, and manufacturing control systems. DeviceNet is one example of a commercial Supervisory Control And Data Acquisition (SCADA) network that is based on the CAN specification. The system is used extensively to link subsystems and sensors using a simple low-cost, two-wire, hot-swappable network. Many infrastructure control systems make use of a CAN or CAN-like network at some point in their layout for connecting remote sensors to indicators and controllers to actuators, or to link multiple controllers to a common user interface.
The CAN protocol continues to experience widespread use in modern electronic systems. Several high-tier European and Japanese automobile models which use CAN are currently available. In automobiles, the CAN system is employed as the Intravehicle Network, or IVN, and may be used for everything from engine control to stereo audio distribution. Other automotive applications include A/C and heating, lighting control, and entertainment/infotainment systems. In addition to standard automobiles, CAN is employed in trucks, for truck-to-trailer communication; in trains, for door units, brake controllers, and ticket validation devices; in maritime electronics, to control pumps and valves; in aircraft, for flight sensors and navigation systems; in medical equipment, for operating room equipment management; and in factory automation systems, for process control and remote data acquisition.
The IEEE 802.15.4 wireless standard was finalized in late 2003. Commercially known as “ZigBee,” this system is designed to operate at low data rates with secure, low cost network configurations. Such a network is commonly referred to as a low-rate wireless personal area network (PAN). PAN networks are often used for home networking, medical instrumentation, and other applications which desire very low power remote sensors in order to optimize battery life and minimize sensor maintenance. Two elements of the IEEE 802.15.4 low-rate wireless PAN standard are low power operation and inherent security implementation.
The IEEE 802.15.4 standard specifies the Medium Access Control (MAC) and Physical (PHY) layers of the protocol stack. The PHY layer provides the analog RF link between two communicating nodes. In particular, the PHY layer of a low-rate wireless PAN network uses direct sequence spread spectrum (DSSS) which offers inherent jamming resistance. The MAC layer defines the frame structure of the message packet, and the handshaking involved in establishing a connection. The IEEE 802.15.4 standard PAN further utilizes a time-slotted Carrier Sense Multiple Access—Collision Avoidance (CSMA-CA) mechanism. Security features are also implemented and include the ability to maintain an Access Control List (ACL) and the ability to perform symmetric cryptography.